Title: Experimental co-infection studies with avian influenza viruses and Newcastle Disease viruses in chickens, turkeys and domestic ducks Authors
|Cha, Ra Mi|
|Sa E Silva, Mariana|
Submitted to: American Association of Veterinary Laboratory Diagnosticians
Publication Type: Abstract Only
Publication Acceptance Date: June 21, 2012
Publication Date: October 20, 2012
Citation: Pantin Jackwood, M.J., Miller, P.J., Afonso, C.L., Spackman, E., Kapczynski, D.R., Shepherd, E.M., Smith, D.M., Cha, R., Sa E Silva, M., Swayne, D.E. 2012. Experimental co-infection studies with avian influenza viruses and Newcastle Disease viruses in chickens, turkeys and domestic ducks [abstract]. American Association of Veterinary Laboratory Diagnosticians. p.139. Technical Abstract: Co-infections of poultry with Newcastle Disease viruses (NDVs) and Avian Influenza viruses (AIVs) present a problem both from the clinical point of view and the diagnosis of these viruses. Little has been done to understand the interactions between these two viruses when infecting poultry. Exposure to NDV, either live vaccines or field strains, is nearly unavoidable for commercial and non-commercial poultry worldwide, so co-infections with avian influenza viruses are expected to occur. The goal of this study was to examine the interaction between NDV and AIV in infected poultry species. We conducted experiments in which we infected chickens, turkeys and domestic ducks with lentogenic, mesogenic or velogenic strains of NDV, and with low pathogenicity (LP) or high pathogenicity (HP) AIV, as relevant to specific ecosystems, by giving one of the viruses first or by giving them simultaneously. Pathogenesis (clinical signs, lesions), presence of the viruses in tissues, duration and titer of virus shedding for each virus, transmission to contact birds, and seroconversion to both viruses were evaluated. Chickens co-infected with a lentogen NDV vaccine strain (LaSota) and a LPAIV (H7N2) responded similarly to infection as chickens infected with the viruses given separately. In turkeys, infection with the LPAIV interfered with the NDV infection, especially if given first. Interestingly, chickens inoculated with a more virulent NDV virus (a mesogenic strain, Pigeon 84) were refractory to infection with a HPAIV (H5N2) if given three days after NDV infection (at the peak of virus replication in tissues). Similarly, previous infection of domestic ducks with a velogenic NDV or a LPAIV (H7N8) interfered with infection with the other virus. In conclusion, previous or simultaneous infection of NDV and AIV can affect the replication dynamics and the disease caused by these viruses in poultry. The information obtained from these studies helps in understanding the interaction of these viruses in the field and improves the diagnosis of these viruses.